Effects of acupuncture on RT-BM1 and maternal-fetal immune tolerance in rats with ovarian hyperstimulation

Abstract

Objective

This study aimed to evaluate the effects of acupuncture on embryo implantation and maternal–fetal immune tolerance in rats with ovarian hyperstimulation, identify the mechanisms of acupuncture treatment, and promote application of acupuncture in the field of assisted reproduction.

Methods

Eighty female Wistar rats were randomized into normal (N), model (M), acupuncture treatment (A), and progesterone treatment (P) groups, with 20 rats in each group. An ovarian hyperstimulation model was established in groups M, A, and P by the peritoneal injection of pregnant mare serum gonadotropin (PMSG) combined with human chorionic gonadotropin (HCG). Bilateral “Sanyinjiao (SP6)”, “Zusanli (ST36)” and “Taichong (LR3)” as acupoints were needled in rats in group A. Rats in group P received an intramuscular injection of progesterone (4 mg/kg). All pregnant rats were treated for seven days. On the 8th day, the pregnant rats were sacrificed for testing. The expression levels of estrogen (E₂) and progesterone (P₄) in serum and their receptors in the endometrium, Th1 and Th2 cytokines in serum and endometrium, RT-BM1 (the counterpart of HLA-G in rats) mRNA, Ly49 activating receptors (Ly49s3, Ly49s5) and inhibitory receptors (Ly49i3, Ly49i4, Ly49i5) on immunocytes in the maternal–fetal interface were detected using ELISA, Western blot, and real-time polymerase chain reaction (PCR).

Results

Compared with group N, the pregnancy rate and the number of implanted embryos were significantly decreased in group M (P < 0.05); E₂ and P₄ levels in serum, and the protein levels of ER-α and Progesterone Receptor (PGR) in the implantation site of endometrial tissue were significantly reduced in group M (P < 0.05); the expression of INF-γ and IL-2 in serum and endometrium were significantly increased, while the expression of IL-4, IL-6, and IL-10 in serum and endometrium were significantly decreased in group M(P < 0.05). The mRNA levels of RT-BM1, Ly49i3, and Ly49i4 receptors in group M were significantly higher than those in group N, whereas the mRNA levels of Ly49i5 and Ly49s5 receptors in group M were significantly lower than those in group N at the maternal–fetal interface (P < 0.05). The pregnancy rate and number of implanted embryos were significantly higher in group A than in group M (P < 0.05). Serum E₂ and P₄ levels were significantly higher in groups A and P than in group M (P < 0.05). The expression of ER-α and PGR in the implantation site of endometrial tissue in group A were significantly higher than those in group M (P < 0.05). The serum levels of INF-γ and IL-2 in group A and group P were significantly lower than those in group M (P < 0.05). The serum expression of IL-4, IL-6, IL-10 in group A and group P were significantly higher than those in group M (P < 0.05). The endometrium expression of INF-γ and IL-2 in group A were significantly lower than those in group M (P < 0.05). The endometrium expression of IL-4, IL-6, IL-10 in group A were significantly higher than those in group M (P < 0.05). The endometrium expression of INF-γ in group P were significantly lower than those in group M (P < 0.05). The endometrium expression of IL-6 and IL-10 in group P were significantly higher than those in group M (P < 0.05). The mRNA levels of RT-BM1 and these Ly49 receptors (except the Ly49s3 receptor) at the maternal–fetal interface of groups A and P were higher than those of group M (P < 0.05).

Conclusion

Acupuncture can significantly increase the pregnancy rate and average number of implanted blastocysts in rats with ovarian hyperstimulation. This mechanism is related to the effects of acupuncture in upregulating the expression of RT-BM1, regulating the balance of Th1/Th2 cytokines, and upregulating the expression of inhibitory receptors in immunocytes.